What are those 'layer' like icons at the top of the Animation Frame Gallery?

I cannot find anywhere where those are identified...

do you mean the B [background] and the O [overlay] ?

Now that you mention it, I think they used to be labeled that way, but now just some multi-layer images within the icons (sometimes icons can be too iconny).

if you hover your mouse over them do you get a description ?

First thing I tried. Nothing.

btw, I have version 7.1.1.17261 (June 7, 2011)

screenshot then please so we know what we are talking about - thanks

Are these the ones you are referring to? Attachment 84153

Hi,
The one on the left is Background layer..this shows on each layer, the one on the right is overlay layer this only shows on that layer and is overlayed. If you place an object on the layer with that selected you can copy the object then add another overlay layer and paste in place then modify then ctrl down arrow and when previewed it will cycle.
Jim

Thanks!